“He plays ornaments and lead-ins I didn’t recall hearing before., and breaks some three-note chords from top to bottom, not bottom to top. Almost totally senza vibrato, but considerable rubato, some necessary for him technically. I hope David Nelson and others will comment.”
The thing (well there are many things) about the Bach unaccompanied violin music is that after all these years and all the editions and great violinists and scholars pouring over this music, and the reasonable quantity of educational material about how to play that we have from the Baroque era, there is still so much about the notation that does not by itself convey exactly what you are supposed to do, and that what Bach was attempting was so distinctive that the “instructional” things we have from that era (books for viol, writings of Quantz, Rameau, Geminiani and others, even Leopold Mozart, which do give good advice about ornaments and such) still do not tell us. Tradition plays a role in this as well, although the HIP violinists distrust it.
A modest example is in the three fugues each one of which poses its own puzzles. There are three and four note chords. Common practice: bottom to top (so in physical terms, left to right, aiming for the E string assuming the top note is on that string. And the top note is therefore assumed to be “the” note with the rest being harmony. But my teachers would take pains to point out, that this or that chord is top to bottom. Nothing in the MS tells you that. Most editions are silent about it too. Partly it is just “what is done.” But another part is, knowing it is a fugue, what part of this chord, what note within it, the top or the bottom part, needs to be primary at THAT chord. Violinists don’t ordinarily have to think in those terms.
It is even harder during those passages when this or that voice of the fugue is not being played or heard but it’s there. somewhere, and Bach throws in a little “here I am!” bit of it now and again. Every chord has to be thought of in those terms. Maybe not all Bach scholars agree on each chord. As one of my teachers was fond of quoting “work out your own salvation, with fear and trembling” (Philippians 2:12). This issue with the direction of chords is most acute in the fugues but exists in the Chaconne and other movements.
It would be interesting to know which edition Kavakos learned from and which one he uses most in his performances.